overheating and found this when head off

phippsey27 · Nov 8, 2014

Hi guys, just been out with my m8 and his 300 tdi started overheating again, we have got head off and have found this (pic) we have a new skimmed head but what has caused this as we now have the valve mark on the piston top too please advise perry

jamesmartin · Nov 8, 2014

gaskets knackered too ,either tappets were too tight,timing slightly off or more likely you need a thicker head gasket or valve seat cutting to let valve sit further in head, valves run very close to piston at tdc exhaust stroke ,when you skim head you let valve sit nearer piston ,you should measure distance from head face to valve face and ensure its within tolerance, most get away with 3 hole gasket but it depends what was skimmed off and if heads been skimmed twice

phippsey27 · Nov 8, 2014

jamesmartin said:
gaskets knackered too ,either tappets were too tight,timing slightly off or more likely you need a thicker head gasket or valve seat cutting to let valve sit further in head, valves run very close to piston at tdc exhaust stroke ,when you skim head you let valve sit nearer piston ,you should measure distance from head face to valve face and ensure its within tolerance, most get away with 3 hole gasket but it depends what was skimmed off and if heads been skimmed twice

as always a true star cheers James, new head is now on with a 3 hole gasket and all seems ok

biolandy · Nov 12, 2014

surprised you didn't hear that knocking

phippsey27 · Nov 13, 2014

No it run sweet as anything, it was just the overheating, anyway new head Now on and running perfect thanks for help

overheating and found this when head off

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